Since in 2005 Google launched Google Maps and popularised the use of raster tile maps in Internet browsers, there have appeared multitude of standards, tools and applications that make possible to create tiles, serve them in an interoperable way through Internet and use them by means of desk or web clients, smartphones or tablets.
Vector tiles, different from raster tiles, include information associated to each of the geographic objects they contain, instead of simply providing their representation as an image.
The technology of vector tiles offers different advantages opposite to raster tiles, that are so commonly used nowadays:
- Vector tiles can be lighter than raster’s depending on the format used to serve them (MapBox indicates that approximately 75% smaller), what is translated in lower consumption of bandwidth, especially interesting in the case of using mobile Internet access plans, and quicker downloads.
- Data visualization is made in client’s side (mobile or desktop app or Internet browser). Thus, app developers can use different styles for their maps with total flexibility.
- Data associated to each map element reach the client, facilitating very quick searches (for example, to show map tips), the selection of visible layers or to adjust user interface to the map the user wants to see. Of course, it´s data provider who decides about the vector representation of the data to serve, their precision, the attributes to include, etc.
The main disadvantage of vector tiles is they require more potent and heavy applications and, so, powerful devices to show them. This point, that in 2005 was an unbeatable restriction, now it´s not a problem for the majority of users thanks to technology evolution.
In the beginning, all geodata formats could be used to create vector tiles to be served by means of standardized interface services. Therefore, there are emerging specialized alternatives adjusted to the particular case of vector tiles:
- Based on data coming from OpenStreetMap, different projects have been offering vector tiles in diverse formats.
- Mapbox has created an open specification for vector tiles that has become a de facto standard as it is demonstrated by the huge quantity of servers, clients and applications that have been developed using it, including the main map viewer clients as Openlayers.
- Geoserver developer’s community has developed extensions that can be installed in the server to offer maps as tiles in several formats, including that of Mapbox.
- Some private companies are starting to include support to this open specification in their products, for example ESRI.
It seems that there is a clear commitment for vector tiles, what makes very probable that in near future the use of this technology will be very spread out, just like it has been during last years in the scope of map servers based on raster tiles.
That is why GeoSLab is collaborating with the National Centre of Geographic Information of Spain in the process of study and implementation of this technology in the frame of the Spatial Data Infrastructure of Spain (IDEE). The objective is proving its utility and impulse its use from a national institution first and then to be translated to a European context (redaction of technical guidelines to be sent to the INSPIRE Directive Experts Committee for evaluation and dissemination).